Thrust augmenting fluid rectifier for a pulsed combustor

Abstract

A thrust augmenting fluid rectifier for a pulsed combustor comprising ducting having a converging inlet section, a flow redirecting section and a diffuser section, the inlet of the ducting being spaced upstream from the combustor inlet to define a thrust augmentor utilizing the backflow from the combustor inlet as primary fluid. In one embodiment the rectifier ducting extends rearwardly to a chamber that combines it with the combustor outlet. Substantial pressure gain is obtainable making the invention suitable for gas turbine applications.

What is claimed is: 
     
       1. A thrust augmenting fluid rectifier for a valveless pulsed combustor having an inlet duct, a combustion chamber, and an outlet duct, comprising ducting having a converging inlet section, a flow redirecting section, a diverging section and an outlet, the converging inlet section of the ducting having an inlet cross-sectional area larger than that of the combustor inlet duct, said converging inlet section being spaced upstream from the combustor inlet duct to define an air intake region and being operative to receive backflow from the combustor and secondary air from the intake region, said flow redirecting section being adapted to redirect fluid flowing through the ducting through substantially 180°. 
     
     
       2. The apparatus of claim 1 further comprising a combining chamber disposed downstream from the combustor outlet duct, and wherein the rectifier ducting extends rearwardly and communicates with said combining chamber for combining the fluid from the ducting with the exhaust from the combustor outlet duct. 
     
     
       3. The apparatus of claim 2 wherein the length of the rectifier ducting is greater than the length of the combustor so that a fluid pulse from the ducting is substantially out-of-phase with a fluid pulse from the combustor outlet duct. 
     
     
       4. The apparatus of claim 1 disposed substantially coaxially within an outer duct, said outer duct including at its downstream end a converging-diverging section, and operative in association with the exhaust from the combustor outlet duct, to provide mass flow augmentation. 
     
     
       5. The apparatus of claim 1 wherein the rectifier ducting comprises a plurality of ducts for receiving backflow from the combustor and secondary air from the intake region. 
     
     
       6. The apparatus of claim 1 wherein the combustor comprises a plurality of inlet ducts and having rectifier ducting associated with each of the inlet ducts. 
     
     
       7. A plurality of the apparatus of claim 2 interconnected so that the rectifier ducting of one apparatus communicates with the combining chamber of another apparatus. 
     
     
       8. The apparatus of claim 1 wherein the rectifier ducting comprises a symmetrical converging-diverging member having a similar inlet and outlet section, each operative to function alternately as an inlet and outlet in conjunction with a pair of combustors spaced therefrom, such that the backflow from one combustor compresses a charge in the other combustor. 
     
     
       9. The apparatus of claim 8 wherein the outlet ducts of the combustors are interconnected.